Putting Your Lawn to Bed for the
Winter

Table of Contents

Introduction

Fall is the time to start putting your lawn to bed for the winter.
Summer has come and gone, and chances are, it has taken its toll
on your lawn. Drought, disease, insects and weeds can leave your
lawn looking thin and patchy (Figure 1). Here
are some tips for getting your lawn back into shape, preparing it
for survival during the winter and a quick green-up in the spring.

Figure 1. Thin, patchy
lawn.

Fertilize turf to help heal damaged lawns. Damaged
areas in turf will recover more quickly with two applications of
fertilizer in the fall. The first application should be made in
early fall (from mid-August to mid-September). This will help turf
recover from damage that occurred during the growing season. Nitrogen
and potash stimulate turf growth and repair, and harden off the
turf for winter. Fertilizer should be applied at a rate to deliver
0.5 kg of nitrogen per 100 m2.

Overseed lawns that have extensive turf damage or loss.
Some damage is too extensive to be fixed with just an application
of fertilizer. For those areas, uniformly distribute the desired
seed mixture in two directions, making sure the seed is in contact
with the soil. Seed-to-soil contact can be enhanced by core aerating
before spreading seed. The recommended species for overseeding are
perennial ryegrass (general recommendation), fine fescue (for shade
or low maintenance) and tall fescue (for drought tolerance). The
seeding rates are as follows:

perennial ryegrass: 2-4 kg/100 m2

fine fescue: 1-3 kg/100 m2

tall fescue: 2-3 kg/100 m2

Rolling newly seeded areas also helps. Water the seeded areas frequently
to ensure good germination. The ideal time for overseeding is also
mid-August to mid-September.

Control thatch in the fall. Thatch harbours disease-causing
organisms such as snow mould. In turf with excess thatch, the growing
point of the plant is elevated above the soil. The soil has insulating
properties that the thatch does not. Lawns with an abundance of
thatch are more prone to winter injury. The ideal time for thatch
control is the same as for overseeding and the first application
of fall fertilizer. There are two major ways of controlling thatch
- core aeration and dethatching. Core aeration cuts cylindrical
plugs out of the lawn (Figure 2), breaking up
the thatch and bringing up soil, which contains microorganisms,
that help break down the thatch. De-thatching, or verticutting,
is done by a machine that cuts into the thatch vertically, bringing
up the debris, which is then raked up and disposed of.

Figure 2. Cylindrical
plugs created by core aeration.

Remove fallen tree leaves before snowfall. If
fallen leaves are not removed, the lawn will not get light and will
eventually die. An alternative to leaf removal is pulverizing tree
leaves with a mulching mower and letting them decompose on your
lawn. Research has shown that a layer of tree leaves up to 15 cm
deep can be mulched in a lawn without adversely affecting it. Mow
dry leaves with a mulching mower with sharp mower blades.

Leave the lawn cut at the right height. Raise
the mowing height slightly in the fall. Rooting depth is proportional
to mowing height - the longer the leaves, the deeper the roots.
Longer grass blades provide some insulation for the crown (growing
point) of the grass plant. However, if the grass is too long going
into the winter, it will become matted, which encourages winter
diseases such as pink and grey snow mould.

Apply a late season fertilizer application. To
ensure good winter survival and early-spring green-up, make this
fertilizer application when the turf has stopped growing but is
still green, usually in mid- to late October. Timing is critical.
Fertilizer applied too early will promote succulent growth in the
fall that will make the lawn more susceptible to winter injury.
Fertilizer applied too late will be of no benefit to the turf. If
you make a late-fall fertilizer application, spring fertilization
can be delayed until late May to early June. The application rate
for this time of the year is the same as for the early fall application
(0.5 kg of nitrogen per 100m2).

Principles of Late-Season Fertilization

Nitrogen is taken up by the roots even though shoot growth
has ceased. This is because roots remain active at cooler temperatures
than shoots.

Increased photosynthesis means increased sugars. Since turf
is not growing at the time of the fertilizer application, the
sugars that are produced are not used for growth but are stored
to enhance winter survival and spring recovery.

These sugars make the grass plant less susceptible to freezing.
A good analogy is that a bottle of juice in the freezer will take
longer to freeze than a bottle of water. The grass plant cells
are full of sugars and hence take longer to freeze, and freeze
at lower temperatures.

Late-season nitrogen applications promote deep rooting during
the fall, so plants go into the spring and summer with deeper,
healthier roots.

Spring green-up is early, because the nitrogen that is stored
in the roots is ready when shoot growth resumes.

Figure 3. The greener
plots received a late fertilizer treatment.

Take advantage of the good growing conditions in the fall to help
your lawn recover from the summer. With the addition of two properly
timed fertilizer applications, your lawn will survive the winter
better, green up earlier in the spring and have deep roots that
will help it withstand next year's summer drought (Figure
3).

This Factsheet was written by Pam Charbonneau, Turfgrass Specialist,
OMAFRA, Guelph.

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